The present invention relates to union devices for pipe joints and more specifically to such a union, which keeps the pipes securely together on being joined, and where the union can only be disconnected using special measures.
When pipes are laid to form an entire pipeline, there is generally the desire of fixing the pipes to each other so that they will not be separated, e.g. should there be settlements in the pipeline trench. When pipes are inserted in existing pipelines, it may be necessary on many occasions to pull the pipes through these pipelines, and in such a case it is necessary that the joints are securely made. In certain cases, there is a requirement that the joints shall withstand a tensile load of up to 2000 kp.
Particularly in lining pipelines, there must not be any parts projecting inwards or outwards of the pipes at the joints, since in both cases the maximum diameter of the relining pipeline will be restricted. Both the joint and the union must therefore lie within the normal wall thickness of the lining pipe.